#!/usr/bin/env python3 
# -*- coding:utf-8 -*-
a, b = 0, 1  # tuple: t = (0, 1),a = t[0] b = t[1]
print("a=", a)
print("b=", b)

a, b = b, a + b
#  等价于tuple: t = (b, a+b),a = t[0] b = t[1]  带入 a = 1,b=1 -> t = (1,1)
print("a=", a)
print("b=", b)
